class Single
{
private:
    static Single *single;  // Initialize to NULL at definition.
    Single();
public:
    static Single *getSingle()
    {
        // if we've already created the singleton, no need to spend the time
        // needed to lock and unlock the mutex
        if ( !single )
        {
            static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

            pthread_mutex_lock( &mutex );

            // need to check again in case another thread created the singleton
            // while this thread was blocked waiting for the mutex
            if ( !single )
            {
                single = new Single();  // Only gets called once, then if() statemenet is false.
            }

            pthread_mutex_unlock( &mutex );
        }
        return single;
    }
};